But while Hoffman's last days may have been clouded by his struggle with his addiction (he had been sober for 23 years until he sought treatment in May 2013 for heroin abuse after suffering a relapse), his illustrious career is what the Oscar winner will seemingly be remembered for—despite the fact that there are now a number of question marks with regards to his unfinished projects.

The Capote star was the middle of filming the upcoming Showtime series Happyish, and, according to a source, the show is "unlikely" to continue after Hoffman's sudden death.

Although nothing has been decided yet, the source said the network fought for more than a year to get the Moneyball actor, who also served as executive producer, on board and he "drives every scene of the pilot."

"It is hard to imagine a way in which it could go on," the source continued. "His role would have to be recast and there weren't any other actors in serious consideration aside from Philip. If the show does move forward, the premiere would be delayed as pilot would need to be reshot."

Showtime picked up 10 episodes of the drama just last month. Upon hearing the news of Hoffman's death, the network released a statement saying, "Philip Seymour Hoffman was one of our generation's finest and most brilliant actors. He was also a gifted comedic talent. It was a great privilege and pleasure to work with him and we are all absolutely devastated by this sudden loss. Our thoughts go out to his family at this very difficult time."

Hoffman was also hard at work on the Hunger Games franchise (he appeared in a supporting role in last year's Catching Fire), however, his role as Head Gamemaker Plutarch Heavensbee in The Hunger Games: Mockingjay—Part 1 was "substantially complete" when the untimely tragedy occurred, a source close to the production confirmed to E! News.

The source added that the actor had seven days remaining to shoot The Hunger Games: Mockingjay—Part 2. His tragic passing "will not affect" the film's scheduled release dates of November 21, 2014, and November 20, 2015, respectively.

"Words cannot convey the devastating loss we are all feeling right now," director Francis Lawrence, author Suzanne Collins, producers Nina Jacobson and Jon Kilik, and Jennifer Lawrence said in a statement on behalf of the cast of the crew of The Hunger Games: Mockingjay Parts 1 & 2, obtained by E! News. "Philip was a wonderful person and an exceptional talent, and our hearts are breaking. Our deepest thoughts and condolences go out to his family."

Hoffman also took his final trip to Sundance last month for the annual film festival in Park City, Utah, where he premiered the John Slattery-directed film God's Pocket. While there, he also promoted the Anton Corbijn-thriller A Most Wanted Man, which also stars Rachel McAdams.

"We spent some time together only two weeks ago and he seemed in a good place despite some issues he had to deal with," Corbijn said after Hoffman's passing. "He was not only the most gifted actor I ever worked with (and judging by the legacy he leaves behind I am certain I share this with most if not all directors who were fortunate enough to work with him), he had also become an incredibly inspiring and supportive friend."

According to The Hollywood Reporter, both projects were bought for distribution. A Most Wanted Man is currently set for release in 2014.

The three-time Tony award-winning star was also set to direct the Prohibition-era drama Ezekiel Moss, starring Amy Adams and Jake Gyllenhaal.

THR reports that Exclusive Media was planning to launch the project to foreign buyers at Berlin's upcoming European Film Market, but now the project will not be brought to Berlin, and producers will be meeting to discuss the future of the film in light of Hoffman's passing.

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